CRISPR is a term for Clustered Regularly Interspaced Short Palidromic Repeats. A number of protein families appear only in association with these repeats and are designated Cas (CRISPR associated) proteins. This family, represented by TM1791 of Thermotoga maritima, is designated Cmr6 [sic], for CRISPR/Cas Ramp Module protein 6. This family is both closely related to and frequently encoded next to the TM1792 family of Cas proteins described by TIGR01867. The two proteins are fused in an example from Methanopyrus kandleri.